The program is concerned with growth control of biological systems through control of specific metabolic transformations involved in the production of essential substances required for growth. A better understanding of metabolic processes is approached through the preparation of intermediates in the processes and a study of their biological reactivity. Modification of the structures of the intermediates and a study of the effect of the modified structures on specific enzymatic transformations, i.e., drug design, is the approach to growth control. The processes of concern in the initial studies are the metabolic transformation of chorismic acid to the essential aromatic amino acids and growth factors in bacteria, molds, and higher plants.